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Watermelon Growing Guide

Grow Big, Juicy Watermelons At Home

Watermelon is the quintessential Summertime treat in most areas of the world. Because of their popularity in home gardens, we get a lot of questions from both beginner and long-time gardeners when Spring garden planning begins. So let’s address the questions we get the most when deciding to grow your watermelons at home.

Are watermelons hard to grow?
In general, watermelons, like other fruits and vegetables, are not particularly difficult to grow. However, they do require a few key things: a lot of sun, adequate water, the correct nutrients (and a lot of them), and most importantly a LOT of space. To grow your watermelons successfully, we recommend starting your plants from seeds and transplanting them into your garden.

Can I grow watermelons vertically?
No doubt you’ve seen plenty of photos and posts out there showing watermelons growing on a chain-link fence or on a trellis. And yes, while it absolutely can be done, it’s not a method that we recommend. Watermelon vines are naturally relatively delicate and tend to sprawl outward, not upward. Supporting large fruits can very easily damage your vines from the weight of the melons. Once watermelons do start producing, they will have to be supported manually and individually tied up so it is a very labor-intensive process. From a harvesting standpoint, growing vertically also eliminates a key factor in determining the ripeness and sweetness of your melon, the field spot (keep reading for more information on this!).

Do watermelons grow in raised beds and containers? 
Of all the questions we get, this may be the most controversial to answer so we are going to preface it by saying, that every garden and gardener is different. And we always encourage you to experiment and do what works for you. With that being said, watermelons crawl and take up a ton of space. No, really, a LOT of space. So if you have a raised bed that is at LEAST 20 sq. ft., you can likely grow a couple of watermelons. But when it comes to growing your own food, we truly believe that optimizing your area to grow different fruits and vegetables is far more worth it. If you’re growing in containers, we 100% do not recommend growing watermelons. 

The 4 Types Of Watermelons

There are lots of different watermelon varieties out there for you to choose from that all have unique qualities from their flavor to the color of the fruit itself. But when choosing a watermelon variety, it’s helpful to know the different types based on your needs. The 4 types of watermelons that all varieties can be broken down into are seedlessiceboxyellow and orange flesh, and picnic

Seedless Watermelons

Seedless watermelons were developed in the 90's to have small edible seeds. Typically produce 10-20 pound fruits and mature in 85 days and require a pollinator variety.

Icebox Watermelons

Specifically bred to be small enough to fit in a refrigerator and feed one person or a small family. Round fruits average between 5-15 pounds and mature in 75 days.

Yellow and Orange Watermelons

Yellow or orange fleshed fruit can be round or oblong shaped, seeded or seedless, and can weigh up to 30 pounds on average. Matures in 75 days.

Picnic Watermelons

The largest watermelon variety weighs in between 16 and 45 pounds. Makes a great option to feed large crowds. Oblong fruits will mature in 85-90 days.

Our Favorite Watermelons to Grow

The Right Time To Plant Watermelon Seedlings

A major contributing factor to having a healthy watermelon crop is to know just how much they hate the cold. Making absolutely certain that any danger of frost has passed will help keep your watermelons healthy and happy.  Aside from the planting calendar below, the best rule of thumb is to make sure that your soil temperature is maintaining an even 70°F for at least 2-3 weeks.
If you are starting your watermelons from seed, be sure and read the “How To Grow Watermelons From Seed” from HOSS University.

Seed Starting Dates

Zone 10 December 15th
Zone 9 January 15th
Zone 8 February 20th
Zone 7 March 15th
Zone 6 April 1st
Zone 5 April 20th

In-Ground Planting Schedule

Zone 10 January
Zone 9 February/March
Zone 8 April
Zone 7 April/May
Zone 6 May
Zone 5 May/June

Transplanting Your Watermelon Seedlings

Once your watermelon seedlings have at least 2 sets of true leaves, the weather is warm enough for the soil to maintain at least 70°F, and the plants have a healthy root system, your seedlings are ready to transplant into the ground.
The most important thing to remember when transplanting watermelons is to take extra care with the root systems. They are very delicate and disturbing them could result in the loss of your plant. 
When the plants can easily be pulled from the seed tray cells, that is a good indication that they are ready to go in the ground. If they don’t come out of the trays easily, that’s okay. You can help them out by very gently pushing them through the hole in the bottom of the 162 cell seed starting tray.

Watermelon Seedling Planting Depth

Row Spacing – 6 to 8 feet
Plant Spacing – 2 to 3 feet
Planting Depth (Plants) – Soil Level

When choosing a spot to plant your watermelons, make sure it has full sun and won’t be shaded by other plants.

Did you know?

The heaviest watermelon to date was grown by Guinness World Record holder Chris Kent, of Sevierville, Tennessee, in 2013. A Carolina Cross, weighed in at 350.5 pounds. That is the average size of an professional NFL linebacker!

Watermelon Soil, Irrigation, & Fertilizer

Watermelon Plant Soil Requirements

  • Loose, well-draining sandy loam
  • pH between 6.0 and 6.5
  • Rich in organic materials
  • Good quality compost added to the soil

HOSS always recommends getting a soil sample to your local extension office several weeks before planting. Once you get your results, you will  need plenty of time to adjust your soil accordingly and make sure your plants are getting the best nutrients possible as soon as they hit the ground.

Click Here to find your local extension office.

Watermelon Irrigation Requirements

Irrigation for your watermelon plants is one of, if not the most important, aspects of growing healthy watermelons. We always recommend using a drip tape irrigation system for several reasons.
1. Once the watermelons have developed a strong vine and foliage, getting water to the root system can be difficult with overhead watering.
2. Watermelons, in general, have typical disease issues. Drip irrigation will help keep moisture off the leaves and at the root system where it’s needed the most. Extended leaf wetness can easily cause disease in your crop.
3. Watermelons don’t do well under stress and improper irrigation is a major stress factor on plants. Drip irrigation ensures each plant is is getting the required amount of moisture.
Overall, the rule of thumb when growing watermelons is that watermelon plants require 1″ – 2″ of water per week while they are growing and producing flowers and fruits. Depending on your zone, if you have more rain during the summer, be sure and account for extra moisture in your irrigation schedule. Once the melons start to produce, decreasing the amount of water weekly will help give you a sweeter fruit during harvesting.

In-Ground Watermelon Fertilizer Schedule

Several Weeks Before Planting

Test your soil at your local extension office.

1 Week Before Planting

After adjusting soil pH to 6.0 – 6.5, mix 1 1/2 cups per 10 ft. of row of Hoss Complete Organic Fertilizer with your soil.

2nd Week After Planting

Using the Hoss Fertilizer Injector, Mix 1 cup of Hoss Premium 20-20-20 Fertilizer -AND -1-2 cups of Hoss Micro-Boost Micronutrient Supplement per 20 ft. of row.

Rotate Every 7 Days After Vines Begin To Run

Mix 1 cup of Hoss Premium Calcium Nitrate -AND -1-2 cups of Hoss Micro-Boost Micronutrient Supplement per 20 ft. of row.

Watermelon Pest & Disease Protection


Organic Controls

Garden Insect Spray

Neem Oil

Monterey Bt

Take Down Garden Spray
Aphids, Thrips

Bug Buster O
Aphids, Thrips

Horticultural Oil
Aphids, Aphids

Diatomaceous Earth

Complete Disease Control

Non-Organic Controls

Liquid Copper
Downy mildew

Garden Phos
Downey mildew, anthracnose, gummy stem blight, damping off (seed treatment)

Vegetable, Flower, Fruit & Ornamental Fungicide
Downey mildew, gummy stem blight, anthracnose

Bug buster ll
Aphids, Thrips, Cutworms

Click to visit the Pest Control product page for specific pest treatments and choosing the right insecticide treatment for your needs.

Treat as needed using label instructions.

Common Diseases

Non-Organic Controls

Liquid cop
downy mildew

Garden Phos
downey mildew, anthracnose, gummy stem blight, damping off (seed treatment)

Complete Disease Control

Vegetable, Flower, Fruit & Ornamental Fungicide
downey mildew, gummy stem blight, anthracnose

Treat as needed using label instructions.

Harvesting And Storing Your Watermelons

How To Know If Your Watermelon Is Ripe and Sweet

South Georgia, where the HOSS HQ is located, is known as being the watermelon capital of the world. Over the years, knowing exactly the right time to harvest watermelons to either sell at market or enjoy at home has become less of a guessing game and more of a trick of the trade. There are several tell tale signs that you can tell a watermelon is ripe. There’s the “thump test” where you can hold your ear up to the melon and, after years of experience thumping melons and knowing exactly what to listen for, you can tell that it’s ripe just by the sound it makes. While this method may be great for some, the thought of thumping acres of melons to tell if they’re ready for harvest isn’t really feasible. So here’s the 2 best ways to tell if your melons are ready for harvest.

Look For The Curly Q

Where the stem of the watermelon meets the main vine, there is a small tendril that comes off of the plant that we call a curly q. This is the best indicator as to the ripeness of your watermelons. When that curly q has completely dried out all the way to the vine, you know that your watermelons are good to harvest. Check out the video in the Extra Credit section below for more detailed info on this method!

Check The Field Spot

While growing, the watermelon rests on the ground and develops what is known as a field spot. A good indication that you’re going to have a ripe and sweeter watermelon is checking the color of this spot. The color ranges from almost white to a deep yellow color. Typically, the darker the yellow spot, the sweeter your watermelon will be. 

How Long Can You Store Watermelons?

After harvesting, watermelons will last in storage for up to 10 days. After cutting your watermelon, they can last in the fridge for up to 5 days. Be sure to keep your uncut watermelons stored at room temperature, though. Putting them in the fridge can cause them to become mealy and lose their sweetness, color and overall flavor.

Shop Our Huge Watermelon Seed Selection!

Watermelon Tips & Tricks

Choosing Sweet Watermelons

While you may think that a shiny, bright green watermelon that you see in photos is the best watermelon to choose, this may not always be the case. Dull melons are good sign that your watermelon is not only ripe, but also sweeter than average. Another good thing to look for are brown spots and lines throughout; this is called “webbing” . For every brown spot you see, that is how many times a bee has touched the pollinating parts of the watermelon flower. The more pollination, the sweeter your watermelon is likely to be. 

Watermelons Are Super Good For You

In addition to being refreshing a delicious on a hot summer day, watermelon has major health benefits. Because of their high water content, enjoying watermelon will not only hydrate you but also has lots of vitamins, minerals, and antioxidants. Just one cup of raw watermelon includes:

  • Fiber
  • Carbohydrates
  • Protein
  • Magnesium
  • Vitamin A
  • Vitamin C
  • Potassium
  • Vitamin B6
  • Lycopene
  • Zero fat, cholesterol or sodium

How Do You Know When Watermelons Are Ripe?

Grow the Best Watermelons Ever

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